The objective is to increase our understanding of biochemical characteristics and responsiveness to hormones of the human endometrium during the reproductive years, during pregnancy, in the perimenopausal period and after the menopause. Most will be conducted in vitro, using endometrial tissue, isolated endometrial glands, epithelial or stromal cells, decidual cells, and endometrial cell lines. Hormonal regulation of endometrial prostaglandin (PG production and the mechanisms by which estrogens, progestins and glucocorticoids exert their actions on PGF2 output will be studied by comparing responses of epithelial and stromal cells and the effects of steroids, peptide hormones and calcium ionophore on the activities of phospholipases, acyltransferases, PG synthetase, and PG metabolizing enzymes. Endometrial prostaglandins are considered to play an important role on dysmenorrhea and dysfunctional bleeding as well as in normal menstruation, implantation and premature or term onset of labor. Levels and regulation of enzymatic activities in decidual cells and in their stromal precursors will be compared to characterize biochemical changes associated with decidualization and labor. Regulation of DNA polymerase Chi activity will be investigated by modifying the time and schedule of exposure of cells in culture to estrogens, progestins and C19 steroids. The activity of this key enzyme for cell proliferation can be stimulated by estradiol but becomes refractory to the hormone by unknown inhibitory mechanisms. Intracellular levels and rates of output of immunoreactive Beta-endorphins detected in preliminary experiments will be measured in tissue and cells and will be related to actions of endogenous hormones or steroids added to the medium. Effects of cholinergic agents, PGs and other test compounds on the conversion of phosphatidylinositol to inositol phosphates will be studied and related to their actions on mucin output, an important physiologic function of the endometrium. The role of sex-steroid binding plasma globulin on the uptake of estrogens by estrogen-responsive cells will be evaluated from steady-state isotopic date obtained during superfusion of cells in suspension.